Transactinide element

A chemical element with atomic number greater than 103. Every known transactinide is radioactive, and all are produced artificially.

Atomic number: The number of protons in an atom’s nucleus, which determines its chemical element. The boundary is defined directly: transactinides have atomic numbers above 103.
Heavy-ion fusion: A nuclear reaction in which two atomic nuclei combine after colliding at high energy. Fusion reactions create most known transactinide nuclei one atom at a time.
Darmstadtium: Synthetic chemical element 110, first reported by a team at GSI in 1994. Its discovery illustrates the fusion experiments used to extend the periodic table.
Copernicium: Synthetic chemical element 112, a highly radioactive transactinide with properties studied atom by atom. Its volatile behavior lets experiments test whether superheavy elements follow periodic trends.
Element 119: A proposed chemical element with atomic number 119 that has not been confirmed. Its synthesis would begin a new period in the periodic table.
Periodic table: A tabular arrangement of chemical elements ordered by atomic number and recurring chemical properties. Transactinides extend the table beyond its traditional actinide region.
Nuclear fusion: A nuclear process in which light nuclei combine to form a heavier nucleus. Heavy-ion fusion is the synthesis route behind many transactinide discoveries.
Oganesson: Synthetic chemical element 118, named in 2016 for physicist Yuri Oganessian. It is the highest-numbered element confirmed to date.
Flerovium: Synthetic chemical element 114, named for the Flerov Laboratory of Nuclear Reactions. Measurements investigate how relativistic effects shape its unusual chemical behavior.
Element 120: A proposed chemical element with atomic number 120 that has not been confirmed. Attempts to create it test production limits beyond the currently known elements.

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